I am at war with my greengrocer. It’s a low-level conflict – there’s no deliberate bruising of produce, no sneaky foreign coin slipped in with my change – but war it is.

You see my greengrocer is triumphantly old-fashioned. None of this modern New Age hippy stuff like “helping yourself”. No, he does all the picking for you. This I like. His rival across the road allows you to choose your own things but stands there watching, arms folded belligerently, as if daring you to reject any of his produce as unsatisfactory. We’re talking about a man with a 5-inch scar across his face which I don’t think he got from handling cucumbers. Wilting under this hard-man stare, I inevitably leave his shop laden with fruit and veg that’s as brown and wrinkled as a Sicilian grandma.

Over the road, there are no such issues. My greengrocer chooses and chooses well. The thing is, as a die-hard traditionalist he has no time for outrageous inventions like cash registers or a pen and paper. Instead, he adds the prices in his head as he goes along, muttering numbers like Dustin Hoffman in “Rain Man” before proudly announcing your final total. He’s never flustered, never makes a mistake. It’s impressive Vordermanesque stuff. But soon I started to notice a pattern. The final total – the only bit of the sum you can clearly hear – is always an odd number: “₤4.43” or “₤7.59” or “₤5.27”. I must have used his shop over 200 times and not once has the total been even, let alone a nice juicy round number like “₤3.50” or “₤4.60” or even – call me crazy – “₤5 exactly”. Surely that’s statistically weird? It’s as if the very specificness of these ₤6.73’s and ₤9.17’s proved he couldn’t be making them up. I felt I was onto something.

Of course, I haven’t said anything, largely because I’m worried he might get the bloke from across the road to show me how he got his scars. Instead, I’ve resorted to more subtle methods.

Last week, I bought some fruit and veg from his shop. The cost: ₤6.37. Two days, a vegetable curry, a ratatouille, two fruit crumbles and an aubergine moussaka later, I went back and, having checked he hadn’t put his prices up, I bought the exact same ingredients. The cost this time: ₤6.61! Surely now I had him! But then I realized the five Golden Delicious I’d asked for might have been bigger than the previous time. Same with the bananas and the cauliflower. There were just too many variables to make a citizen’s arrest. It was back to the drawing board and a family absolutely desperate for some red meat.

By now you’re probably thinking I should get out more – at least to the local supermarket – and you’re probably right. The problem is I’m a numbers geek. Some of my best friends are numbers. I can’t wait to write cheques on the 6th June this year (06/06/06). I love that my house number (59) is a prime number divisible only by 1 and itself. For me, numbers must be respected. I can’t forgive the football manager I heard the other day talking about his lads giving 210%. It was bad enough when everyone gave 110%. At this rate, it’ll soon be as bad as pre-war Germany where you could give 1,000,000% in the morning but it would all be worthless by the afternoon.

That’s why it’s not about money with my greengrocer friend. I just feel if he’s going to cheat, he should cheat better: throw in an even number or even a “Would you believe it? ₤10 exactly!” If not, I’ll do everything I can to expose his behaviour. I’ll give it 423%.